Rotatable punch for tube bender



March 1970 P. v. GREGG 3,499,309

ROTATABLE PUNCH FOR TUBE BENDER Filed Nov. 20, 1967 INVENTOR.

3,499,309 ROTATABLE PUNCH FOR TUBE BENDER Paul V. Gregg, Racine, Wis., assignor to Walker Manufacturing Company,Racine, Wis., a corporation of Delaware Continuation-impart of application Ser. No. 596,859, Nov. 25, 1966. This application Nov. 20, 1967, Ser. No.

Int. Cl. B21d 9/07 US. Cl. 72389 Claims ABSTRACT OF THE DISCLOSURE A bending punch for a tube bender is adjustably mounted on the ram so that its angular position can be varied to locate indentations on the punch as desired with respect to a tube being bent.

RELATED APPLICATION This application is a continuation-in-part of Ser. No. 596,859, filed Nov. 25, 1966.

BACKGROUND OF THE INVENTION In Ser. No. 596,859 is disclosed a machine and method for reducing or eliminating undesired distortions in a tube during bending which involves the use of indentations in the bending punch of a press bender. One of the features in the copending application is the use of a relief in the bending punch to prevent the end of a pipe fro-m going out of square when the bend is formed close to that end of the pipe. The location of this relief in the punch with respect to the end of the tube is important to its proper functioning and with normal punch mounting arrangements it has been necessary to use different punches for different locations of the bend when it was desired to take advantage of the relief.

Accordingly, it is the purpose of the present invention to provide a mounting means for a punch which will enable it to be located in different angular position that may vary as much as on either side of center, thus enabling the same punch to be used for making bends having a number of different locations with respect to the end of the pipe.

BRIEF SUMMARY OF THE INVENTION The invention achieves the above purpose by means of a punch holder which has a cylindrical surface located on the center line of the bending punch and which surface is capable of limited rotary positioning with respect to the axis of the ram prior to tightening of the ram punch structure in a relatively fixed relationship.

' DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front elevation, partly schematic and partly broken away, of a press bender utilizing a punch and mounting in accordance with the invention;

FIGURE 2 is a front elevation similar to FIGURE 1 but illustrates the relative position of the parts during a bending operation;

FIGURE 3 is an enlarged side view taken on the line 3 of FIGURE 4;

FIGURE 4 is an enlarged section along the line 4-4 of FIGURE 1;

FIGURE 5 is a side elevation of a fragment of the punch showing the relief that is used to control deformation on the end of the pipe; and

FIGURE 6 is a side elevation of a pipe that has been bent by the punch of the preceding figures.

- United States Patent O 3,499,309 Patented Mar.'10, 1970 DESCRIPTION OF THE INVENTION The pipe or tube P may be bent to shape P by the bending mechanism 1 by laying it in the arcuate groove 3 of the pivoted wing dies 4 and 4 when the punch 5 which is carried by the ram 9 is in a position somewhat elevated from that shown in FIG. 1. The punch 5 is semi circular and has an arcuate groove 11 in its outer periphery that is in alignment with the grooves 3 of the wing dies so that the grooves 3 and 11 are substantially the cross-sectional configuration and size of the pipe being bent. Upon lowering of the ram 9 the punch 5 presses against the top of the pipe P and the wing dies 4 and 4 pivot downwardly about their pivot shafts 13 and 15 as indicated in FIGURE 2. In accordance with the invention of Ser. No. 596,859, a series of grooves or indentations 17 are for-med in the bottom of the punch groove 11 and these result in the formation of ribs 19 on the inner surface 21 of the pipe P after bending as illustrated in FIG. 6. The production by the indentations 17 of the ribs 19 provides a controlled flow of excess metal on the inside of the bend and eliminates the many defects normally found in bends made by apparatus of the type illustrated.

When the bend is located close to the end of the pipe, as it is in the pipe P shown in the drawings, there is a tendency for the end surface 23 to go out of a plane normal to the axis of the pipe, that is, to go out of square. The copending application has disclosed that this condition can be prevented by the formation of a relief groove 25 in the bottom of the channel 11 in the punch 5 provided the groove 25 is located adjacent the end face 23 during bending, as indicated in FIG. 2. When the bends are located at different distances from the ends 23 of different pipes (as is the case in automobile tailpipes) the grooves 25 must be located in different angular positions with respect to a vertical plane through the axis of the ram 9. The present invention permits the punch 5 to be angularly adjusted so that the groove 25 can be shifted in angular position as desired as much or more than about 20 in either direction.

In order to secure the angular adjustment just mentioned the punch 5 is carried by a punch holder 27 which has a semi-circular cylindrical surface 29 on its top face which fits in a corresponding cylindrical surface 31 on the bottom of an adapter 33 which is mounted on the bottom of the ram 9. The adapter block 33 slides into a re-entrant slot 35 formed in the bottom end. of the ram 9 and is firmly held in position by means of the clips 37 which are compressed against opposite ends of the block and the ram by means of the bolts 39, as is conventional practice in the press benders. The adapter block 33 has a pair of counter-sunk holes 41 located along its midplane which receives the cap screws 43 in such a manner that they are completely housed within the block. The lower ends of the cap screws thread into modified T- nuts 45 which when the screws 43 are loosely attached may slide in T-slots 47 opening out of the top of cylindrical surface 29 of the punch holder 27. The T-slots 47 are of circular shape and concentric with the surface 29 and with the center of the circular groove 11 in the punch 5. When the screws 43 are loose the punch holder 27 may be shifted angularly to different positions with respect to the axis of the ram 9 and then fixedly secured in a desired angular position by simply tightening the cap screws and nuts 45.

The punch holder 27 has vertically extending grooves or recesses 49 formed on opposite ends to receive vertically extending cap screws 51. These extend through suitable openings in a bearing plate 53 that fits in a recess 55 formed in the top surface 57 of the punch 5 and threads into holes 59 in the top of the punch. Thus, the

3 punch holder 27 is fixedly secured to the punch 5 and forms an extension of the punch that can be adjustably mounted in the adapter 33.

Modifications may be made in the structure illustrated Without departing from the spirit and scope of the invention.

What is claimed is:

1. In a press bender for bending tubes and having a ram movable along an axis, an adapter block removably secured to the ram for movement with it, a bending punch having a circular groove for engagement with the pipe to be bent, and means mounting the punch on the adapter block including a circular surface concentric with said groove, and fasteners for fixing the angular position of the punch on the curved surface, said circular groove having a relief therein to prevent angular distortion of the end plane of a pipe being bent, said mounting means providing for location of the relief at different angular locations with respect to the axis and comprising a punch holder bolted to the top of the punch and having said circular surface on top, the top of the punch holder having T-slots opening into it, T-nuts slidable in said T-slots, said fasteners being threaded into said T-nuts and carried by said adapter block.

2. In a press bender for bending tubes and having a ram, an adapter block removably secured to the ram for movement with it, a bending punch having a substantially circular groove for engagement with the pipe to be bent, a punch holder secured to the punch and mounted on the adapter block, the mounting of the holder on the block including substantially circular surfaces on the top and bottom faces of the holder and block respectively and fasteners for fixing the angular position of the punch on the circular surfaces, said circular surfaces being substantially concentric with said groove.

3. A mechanism as set forth in claim 2 wherein said circular groove has an indentation therein adapted to control distortion of a pipe during bending and said circular surface mounting provides for location of the indentation at different angular locations with respect to the axis of ram movement.

4. A mechanism as set forth in claim 3 wherein said indentation is a relief to prevent angular distortion of the end plane of a pipe being bent.

5. In a press bender for bending tubes and having a ram, an adapter block removably secured to the ram for movement with it, a bending punch having a substantially circular groove for engagement with the pipe to be bent, means mounting the punch on the adapter block, a pair of movable wing dies having grooves for engagement with the pipe to be bent, said circular groove on said punch having a transverse relief formed therein to extend across the groove to provide for control of pipe distortion and prevent angular distortion of the end plane of the pipe being bent.

References Cited UNITED STATES PATENTS 2,955,639 10/1960 Brown 72-381 CHARLES W. LANHAM, Primary Examiner L. A. LARSON, Assistant Examiner U.S'. C1.X.R. 72-473 

